Business methods using an optical reader having partial frame operating mode

ABSTRACT

A method of conducting a business transaction involving information recorded in an encoded indicium using an optical reader having a 2D image sensor that is configured to operate in a partial frame capture mode. In a partial frame operating mode, the reader clocks out and captures at least one partial frame of image data having image data corresponding to less than all of the pixels of an image sensor pixel array. In one embodiment, the reader operating in a partial frame operating mode captures image data corresponding to a linear pattern of pixels of the image sensor, reads the image data, attempts to decode for a decodable 1D symbol which may be represented in the image data, and captures a full frame of image data if the image data reading reveals a 2D symbol is likely to be present in a full field of view of the 2D image sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and is acontinuation-in-part of co-pending U.S. patent application Ser. No.09/766,806, filed Jan. 22, 2001, which application is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The invention relates to optical readers in general and inparticular to methods for operating an optical reader having a 2D imagesensor.

BACKGROUND OF THE PRIOR ART

[0003] Optical readers having 2D image sensors commonly are used to readboth 1D and 2D symbols. Some optical readers having a 2D image sensorread a 1D symbol by capturing a 2D image representation, or “frame” ofimage data corresponding to a target area which comprises a 1D symbol,and launching a scan line or lines in order to attempt to decode for 1Dsymbols which may be represented in the area. Other optical readershaving 2D image sensors read 1D symbols by capturing a 2D imagerepresentation of an area containing the 1D symbol, preliminarilyanalyzing the image data represented in the area to determine that theimage data comprises a representation of a 1D symbol, and then launchinga scan line in an attempt to decode for the 1D symbol determined to bepresent. In either case, a full frame 2D image representation iscaptured in order to decode for a 1D symbol.

[0004] Capturing a 2D image representation requires a substantial amountof time, especially in applications wherein one or more “test” frames ofimage data must be captured prior to capture of a frame that issubjected to processing. Furthermore, assuming a constant processingspeed, the time required for an optical reader to capture a 2D imagerepresentation increases with the resolution of the image sensor whichis incorporated in the reader. Currently available CMOS mega pixel imagesensors have low frame clock out rates of about 15 frames per second(FPS).

[0005] A user's satisfaction with an optical reader often variesdirectly with the decoding speed of the optical reader. Given thathigher resolution, including mega pixel readers, are expected to grow inpopularity, the frame capture time will become an increasingly importantfactor for consideration in performance of an optical reader.

SUMMARY OF THE INVENTION

[0006] The invention relates to a method for configuring an opticalreader having a 2D image sensor so the reader captures and processesimage data at higher speeds. Capturing a 2D image representationrequires a substantial amount of time, especially in applicationswherein one or more “test” frames of image data must be captured priorto capture of a frame that is subjected to processing as has beenexplained in commonly assigned U.S. patent application Ser. No.09/766,922, entitled “Optical Reader Having Reduced ParameterDetermination Delay,” filed Jan. 22, 2001, and incorporated herein byreference in its entirety. A 1D or 2D symbol that represents informationand that is amenable to imaging and being recognized using a 2D imagesensor is referred to generically herein as an encoded indicium. Objectscarrying 1D or 2D symbols indicative of the object's identity orquality, of the contents of an object (such as a package), or thatprovide other information, are frequently used in performing business orcommercial activities. Higher speed is useful in commercial or businesssettings. Higher speed permits greater productivity per unit of time,and concomitantly, allows reductions in cost through reductions in thenumber of imaging devices and or personnel required to accomplish agiven repetitive task.

[0007] As will be understood by those of ordinary skill, the terms“commercial transaction” and “business transaction” as used hereininclude both transactions that involve an agreement or promise for whichconsideration is exchanged and the activities that may be conducted inpreparation for or in completion of such agreements, as well asinteractions that are unilateral, such as the making of a gift (apromise for which consideration is not exchanged), or internalactivities within an organization, such as maintaining inventoryrecords, maintaining personnel records or records of assets, or otheractivities that an be categorized as “overhead” in a business context.Activities performed in governmental or quasi-governmental settings arealso contemplated, such as the use of encoded indicia by suchorganizations as the United States Postal Service and the military, aswell as by State and local governmental agencies.

[0008] In some embodiments, the encoded indicium is a symbol thatcomprises a plurality of fields or regions. An example of such anencoded indicium is a check or bank draft, which represents a payment ofmoney, and which is a two-dimensional document having a plurality offields, such as a date, a payee, an amount, a signature of a maker, andinformation regarding a financial institution holding the fundsrepresented by the check, and an account against which the funds arepayable.

[0009] According to the invention, a control circuit of an opticalreader equipped with a 2D image sensor is configured to operate in apartial frame operating mode. In a partial frame operating mode, thecontrol circuit clocks out and captures less than a full frame of imagedata and processes that image data. The control circuit may process theimage data of the partial frame, for example, by reading the image datafrom memory and outputting the image data to an output location such asa display device or a processor system in communication with the reader,by reading and attempting to decode decodable symbols which may berecorded in the partial frame, or by reading and performing opticalcharacter recognition on characters represented in the partial frame ofimage data.

[0010] In one embodiment, the partial frame operating mode is employedto clock out and capture image data corresponding to at least one linearpattern sufficient so that a 1 D symbol in the field of view of theimage sensor may be decoded without clocking out and capturing an entireframe of image data. The partial frame of image data that is clocked outfrom the image sensor during the partial frame capture operating modemay be, for example, a row of symbols at or near the center of the imagesensor or a limited number of lines of image data corresponding to pixellocations of the image sensor, possibly at varying angular orientations.The control circuit may be configured so that if the control circuitcannot decode a 1D symbol during the course of operating in the partialframe capture mode, or detects that a 2D symbol is represented in thecaptured image data, the control circuit switches operation to a fullframe capture mode.

[0011] In another embodiment, the partial frame operating mode isemployed to clock out and capture pixel values corresponding to agrouping of pixels at or near a center of an image sensor other than alinear pattern of pixels. This embodiment may be advantageously employedin cases where decodable symbols are expected to be concentratedproximate a center of an image sensor's field of view. A control circuitmay be configured so that if the control circuit cannot decode a symbolrepresented in the partial frame, or determines that a symbol isrepresented partially or entirely outside the image data of the partialframe, the control circuit automatically switches operation to a fullframe image capture mode.

[0012] In one aspect, the invention features a method of conducting abusiness transaction involving information recorded in an encodedindicium. The method comprises the steps of operating an optical readerhaving a 2D image sensor; capturing with the 2D image sensor a partialframe of image data from an encoded indicium; and processing image dataof the partial frame of image data to extract information encoded by theencoded indicium whereby the purposes of the business transaction areadvanced.

[0013] In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a linear pattern of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a plurality of angularly offset linear patterns ofpixels. In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a plurality of vertically spacedapart horizontally oriented linear patterns of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a grouping of pixels about a center of the imagesensor. In one embodiment, the processing step includes the step ofreading the image data out of a memory device. In one embodiment, theprocessing step includes the steps of reading the image data out of amemory device and attempting to decode for a decodable symbol which maybe represented in the image data.

[0014] In one embodiment, the method further includes the step ofcapturing a full frame of image data if the processing step reveals thata 2D symbol is likely partially represented in the partial frame ofimage data.

[0015] In one embodiment, the method further includes the step ofcapturing an adaptively positioned partial frame of image data if theprocessing step reveals that a 2D symbol is likely partially representedin the partial frame of image data.

[0016] In one embodiment, the processing step includes the step ofattempting to decode for a decodable symbol represented in the imagedata, the method further including the step of capturing a full frame ofimage data if the processing step reveals that a 2D symbol is likelypartially represented in the partial frame of image data.

[0017] In another aspect, the invention relates to a method ofconducting a business transaction involving information recorded in anencoded indicium. The method comprises the steps of: (a) operating anoptical reader having a 2D image sensor; (b) in a partial frameoperating mode, capturing a partial frame of image data, the partialfrom of image data including at least a portion of the encoded indicium;(c) attempting to extract information encoded by the encoded indiciumfrom the captured partial frame of image data; and (d) if in step (c)the reader fails to extract information encoded by the encoded indicium,switching operation of the reader to a full frame capture mode.

[0018] In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a linear pattern of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a plurality of angularly offset linear patterns ofpixels. In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a plurality of vertically spacedapart horizontally oriented linear patterns of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a grouping of pixels about a center of the imagesensor.

[0019] In still another aspect, the invention relates to a method ofconducting a business transaction involving information recorded in anencoded indicium. The method comprises the steps of: (a) operating anoptical reader having a 2D image sensor; (b) in a partial frameoperating mode, capturing a partial frame of image data, the partialfrom of image data including at least a portion of the encoded indicium;(c) attempting to extract information encoded by the encoded indiciumfrom the captured partial frame of image data; and (d) if in step (c)the reader fails to extract information encoded by the encoded indicium,switching operation of the reader to a second partial frame capturemode.

[0020] In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a linear pattern of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a plurality of angularly offset linear patterns ofpixels. In one embodiment, the capturing step includes the step ofcapturing image data corresponding to a plurality of vertically spacedapart horizontally oriented linear patterns of pixels. In oneembodiment, the capturing step includes the step of capturing image datacorresponding to a grouping of pixels about a center of the imagesensor. In one embodiment, the method further comprises the step ofswitching operation of the reader to a full frame operating mode if thereader fails to extract information encoded by the encoded indicium fromdata captured using the second partial frame capture mode.

[0021] In yet another aspect, the invention features an apparatus forconducting a business transaction involving information recorded in anencoded indicium. The apparatus comprises an optical reader having a 2Dimage sensor configured to image an encoded indicium; a control moduleconfigured to operate the 2D image sensor to capture a partial frame ofimage data from the encoded indicium; and a processing module configuredto process the partial frame of image data to extract therefrominformation encoded by the encoded indicium, whereby the purposes of thebusiness transaction are advanced.

[0022] In one embodiment, the apparatus further comprises an analysismodule configured to deduce that a 2D encoded indicium is present in thepartial frame of image data. In one embodiment, the apparatus furthercomprises a control module that configures the 2D sensor to operate in afull frame operating mode.

[0023] In one embodiment, the apparatus further comprises a sensormodule configured to sense that a 2D encoded indicium is present in thepartial frame of image data. In one embodiment, the apparatus furthercomprises a control module that configures the 2D sensor to operate in asecond partial frame operating mode.

[0024] The foregoing and other objects, aspects, features, andadvantages of the invention will become more apparent from the followingdescription and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The objects and features of the invention can be betterunderstood with reference to the drawings described below, and theclaims. The drawings are not necessarily to scale, emphasis insteadgenerally being placed upon illustrating the principles of theinvention. In the drawings, like numerals are used to indicate likeparts throughout the various views.

[0026]FIGS. 1a-1 g illustrate various image data patterns that may becaptured by an optical reader operating in a partial frame capture modeaccording to the invention;

[0027]FIG. 2a is a block diagram of an optical reader of a type in whichthe invention may be incorporated;

[0028]FIGS. 2b-2 h show various types of optical reader housings inwhich the invention may be incorporated;

[0029]FIG. 3 is a flow diagram showing an illustrative process in whicha partial frame of an image of an encoded indicium is processed extractencoded information, according to principles of the invention;

[0030]FIG. 4 is another flow diagram showing an illustrative process inwhich a partial frame of an image of an encoded indicium is processed toextract encoded information, according to principles of the invention;and

[0031]FIG. 5 is yet another flow diagram showing an illustrative processin which a partial frame of an image of an encoded indicium is processedto extract encoded information, according to principles of theinvention.

DETAILED DESCRIPTION

[0032] Encoded indicia, including 1D and 2D symbols such as bar codes,stacked bar codes, and two dimensional encoded symbologies, are commonlyused in many business settings. Some representative examples include thelabeling of goods and/or packages containing the goods, the use ofencoded indicia to identify documents (for example patient records in ahospital or managed health care facility), and the use of encodedindicia to reduce the possibility of fraud or the use of counterfeitdocuments (such as the addition of encoded indicia to drivers'licenses). As already alluded to, some commonly used adjuncts tobusiness transactions, such as checks or bank drafts, can also beconsidered as encoded indicia having a plurality of fields or regions inwhich encoded information is present.

[0033] Referring to FIGS. 1a-1 g, there is shown an optical readerequipped with a 2D image sensor that is configured to operate in apartial frame capture mode. In a partial frame clock out mode, a controlcircuit of an optical reader clocks out (or “reads”) electrical signalscorresponding to less than all of the 2D image sensor's pixels, andcaptures image data corresponding to the pixel locations into memory. Itshould be understood that while the 2D image sensor can view, or image,the entire area from which illumination is provided to its pixels, inthe partial frame mode contemplated, only a subset of such pixels areactually interrogated or caused to provide electrical signals that arethen used for analysis. The partial frame mode is controlled by acontrol module, as will be explained in greater detail below. Thepartial frame of image data is processed using a processing moduleconfigured to extract information encoded by the encoded indicium, aswill be explained in greater detail below.

[0034] Partial frames of image data which may be clocked out andcaptured by an optical reader control circuit (or control module) duringa partial frame capture mode are illustrated in FIGS. 1a-1 g in whichvalid zones 12 represent frame image data corresponding to image sensorpixel positions that are clocked out and invalid zones 14 representpotential image data positions corresponding to pixel positions that arenot clocked out.

[0035] Border 10 defines the full field of view of an optical reader inthe case the reader is operated in a full frame captured mode whilesymbols 16-1, 16-2, 16-3, 16-4, 16-6 and 16-7 are symbols entirelywithin the full field of view of an optical reader defined by border 10but are only partially within certain valid zones shown. Valid zones12-1, 12-3, 12-7, 12-8, 12-9, 12-10, and 12-13 are valid zones of imagedata that partially contain representations of a decodable symbol whilevalid zones 12-11 and 12-12 are valid zones of image data capturedduring a partial frame capture mode which contain representations of anentire decodable symbol.

[0036] In the examples illustrated with reference to FIGS. 1a-1 d anoptical reader operating in a partial frame clock out mode clocks outelectrical signals corresponding to linear patterns of pixels. It isuseful to cause a reader to clock out electrical signals correspondingto linear patterns as shown in FIGS. 1a-1 d when a reader will be usedto decode mainly 1D linear bar code symbols.

[0037] In the examples illustrated with reference to FIGS. 1e, 1 f and 1g an optical reader operating in a partial frame clock out mode clocksout electrical signals corresponding to non-linear groupings of pixels.It is useful to cause a reader to clock out electrical signalscorresponding to pixel groupings as shown in FIGS. 1e, 1 f and 1 g whena reader will be used to decode symbols which are expected to be withina certain position in an image sensor's field of view.

[0038] A reader may be configured so that the reader automaticallyswitches out of partial frame capture mode on the sensing of a certaincondition. For example a reader according to the invention may be madeto switch out of partial frame capture operating mode and into a fullframe capture mode on the sensing that a 2D symbol is partiallyrepresented in the partial frame of image data, or on the condition thatprocessing of the partial frame of image data fails to result in imagedata being decoded. The control module can control the mode of operationof the reader based upon instructions provided in a computer programoperating on an electronic processor, and can cause the reader tooperate in either of the partial frame capture mode or the full framecapture mode, as appropriate.

[0039] An optical reading system in which the invention may be employedis described with reference to the block diagram of FIG. 2a.

[0040] Optical reader 110 includes an illumination assembly 120 forilluminating a target object T, such as a 1D or 2D bar code symbol, andan imaging assembly 130 for receiving an image of object T andgenerating an electrical output signal indicative of the data opticallyencoded therein. Illumination assembly 120 may, for example, include anillumination source assembly 122, together with an illuminating opticsassembly 124, such as one or more lenses, diffusers, wedges, reflectorsor a combination of such elements, for directing light from light source122 in the direction of a target object T. Illumination assembly 120 maycomprise, for example, laser or light emitting diodes (LEDs) such aswhite LEDs or red LEDs. Illumination assembly 120 may include targetillumination and optics for projecting an aiming pattern 127 on targetT. Illumination assembly 120 may be eliminated if ambient light levelsare certain to be high enough to allow high quality images of object Tto be taken. Imaging assembly 130 may include an image sensor 132, suchas a 1D or 2D CCD, CMOS, NMOS, PMOS, CID OR CMD solid state imagesensor, together with an imaging optics assembly 134 for receiving andfocusing an image of object T onto image sensor 132. The array-basedimaging assembly shown in FIG. 2a may be replaced by a laser array basedimaging assembly comprising multiple laser sources, a scanningmechanism, emit and receive optics, at least one photodetector andaccompanying signal processing circuitry.

[0041] The partial frame clock out mode is readily implemented utilizingan image sensor which can be commanded by a control module to clock outpartial frames of image data or which is configured with pixels that canbe individually addressed. Using CMOS fabrication techniques, imagesensors are readily made so that electrical signals corresponding tocertain pixels of a sensor can be selectively clocked out withoutclocking out electrical signals corresponding to remaining pixels of thesensor. CMOS image sensors are available from such manufacturers asSymagery, Pixel Cam, Omni Vision, Sharp, National Semiconductor,Toshiba, Hewlett-Packard and Mitsubishi. A partial frame clock out modecan also be carried out by selectively activating a frame dischargesignal during the course of clocking out a frame of image data from aCCD image sensor, as is explained in U.S. patent application Ser. No.09/766,922, entitled “Optical Reader Having Reduced ParameterDetermination Delay,” previously incorporated herein by reference.

[0042] Optical reader 110 of FIG. 2a also includes programmable controlcircuit (or control module) 140 which preferably comprises an integratedcircuit microprocessor 142 and an application specific integratedcircuit (ASIC 144). The function of ASIC 144 could also be provided by afield programmable gate array (FPGA). Processor 142 and ASIC 144 areboth programmable control devices which are able to receive, to outputand to process data in accordance with a stored program stored in memoryunit 145 which may comprise such memory elements as a read/write randomaccess memory or RAM 146 and an erasable read only memory or EROM 147.Other memory units that can be used include EPROMs and EEPROMs. RAM 146typically includes at least one volatile memory device but may includeone or more long term non-volatile memory devices. Processor 142 andASIC 144 are also both connected to a common bus 148 through whichprogram data and working data, including address data, may be receivedand transmitted in either direction to any circuitry that is alsoconnected thereto. Processor 142 and ASIC 144 differ from one another,however, in how they are made and how they are used. The processingmodule that is configured to extract information encoded by the encodedindicium employs some or all of the capabilities of processor 142 andASIC 144, and comprises the hardware and as necessary, software and orfirmware, required to accomplish the extraction task, including asnecessary decoding tasks to convert the raw data of the image to theinformation encoded in the encoded indicium.

[0043] More particularly, processor 142 is preferably a general purpose,off-the-shelf VLSI integrated circuit microprocessor which has overallcontrol of the circuitry of FIG. 2a, but which devotes most of its timeto decoding image data stored in RAM 146 in accordance with program datastored in EROM 147. Processor 144, on the other hand, is preferably aspecial purpose VLSI integrated circuit, such as a programmable logicarray or gate array that is programmed to devote its time to functionsother than decoding image data, and thereby relieves processor 142 fromthe burden of performing these functions.

[0044] The actual division of labor between processors 142 and 144 willnaturally depend on the type of off-the-shelf microprocessors that areavailable, the type of image sensor which is used, the rate at whichimage data is output by imaging assembly 130, etc. There is nothing inprinciple, however, that requires that any particular division of laborbe made between processors 142 and 144, or even that such a division bemade at all. This is because special purpose processor 144 may beeliminated entirely if general purpose processor 142 is fast enough andpowerful enough to perform all of the functions contemplated by thepresent invention. It will, therefore, be understood that neither thenumber of processors used, nor the division of labor there between, isof any fundamental significance for purposes of the present invention.

[0045] With processor architectures of the type shown in FIG. 2a, atypical division of labor between processors 142 and 144 will be asfollows. Processor 142 is preferably devoted primarily to such tasks asdecoding image data, once such data has been stored in RAM 146,recognizing characters represented in stored image data according to anoptical character recognition (OCR) scheme, handling menuing options andreprogramming functions, processing commands and data received fromcontrol/data input unit 139 which may comprise such elements as trigger174 (see FIG. 2f) and keyboard 178 (see FIG. 2g) and providing overallsystem level coordination.

[0046] Processor 144 is preferably devoted primarily to controlling theimage acquisition process, the A/D conversion process and the storage ofimage data, including the ability to access memories 146 and 147 via aDMA channel. The A/D conversion process can include converting analogsignals to digital signals represented as 8-bit (or gray scale)quantities. As A/D converter technology improves, digital signals may berepresented using more that 8 bits. Processor 144 may also perform manytiming and communication operations. Processor 144 may, for example,control the illumination of LEDs 122, the timing of image sensor 132 andan analog-to-digital (A/D) converter 136, the transmission and receptionof data to and from a processor external to reader 110, through anRS-232, a network such as an Ethernet or other packet-basedcommunication technology, a serial bus such as USB, and/or a wirelesscommunication link (or other) compatible I/O interface 137. Processor144 may also control the outputting of user perceptible data via anoutput device 138, such as a beeper, a good read LED and/or a displaymonitor which may be provided by a liquid crystal display such asdisplay 182 (see FIGS. 2e and 2 g). Control of output, display and I/Ofunctions may also be shared between processors 142 and 144, assuggested by bus driver I/O and output/display devices 137″ and 138′ ormay be duplicated, as suggested by microprocessor serial I/O ports 142Aand 142B and I/O and display devices 137′ and 138′. As explainedearlier, the specifics of this division of labor is of no significanceto the present invention.

[0047] Some or all of the above optical and electronic components may beincorporated in an imaging module as are described in commonly assignedU.S. patent application Ser. No. 09/411,936, incorporated herein byreference in its entirety.

[0048]FIGS. 2b-2 g show examples of types of housings in which the 2Dimager of the present invention may be incorporated. FIGS. 2b-2 g show1D/2D optical readers 110-1, 110-2 and 110-3. Housing 112 of each of theoptical readers 110-1 through 110-3 is adapted to be graspable by ahuman hand and has incorporated therein at least one trigger switch 174for activating image capture and decoding and/or image capture andcharacter recognition operations. Readers 110-1 and 110-2 includehard-wired communication links 179 for communication with externaldevices such as other data collection devices or a host processor, whilereader 110-3 includes an antenna 180 for providing wirelesscommunication to an external device or a host processor.

[0049] In addition to the above elements, readers 110-2 and 110-3 eachinclude a display 182 for displaying information to a user and akeyboard 178 for enabling a user to input commands and data into thereader. Control circuit 140 may cause a graphical user interface (GUI)to be displayed on display 182. A pointer on the GUI may be moved by anactuator or actuators protruding from housing 112.

[0050] Any one of the readers described with reference to FIGS. 2b-2 gmay be mounted in a stationary position as is illustrated in FIG. 2hshowing a generic optical reader 110 docked in a scan stand 190. Scanstand 190 adapts portable optical reader 110 for presentation modescanning. In a presentation mode, reader 110 is held in a stationaryposition and an indicium-bearing article is moved across the field ofview of reader 110. By comparison, in a hand-held mode, the reader 110is manually positioned so that the 2D imager can view an encodedindicium within a target area of the reader.

[0051] As will become clear from the ensuing description, the inventionneed not be incorporated in a portable optical reader. The invention mayalso be incorporated, for example, in association with a control circuitfor controlling a non-portable fixed mount imaging assembly thatcaptures image data representing image information formed on articlestransported by an assembly line, or manually transported across acheckout counter at a retail point-of-sale location. Further, inportable embodiments of the invention, the reader need not be hand held.The reader may part or wholly hand worn, finger worn, waist worn or headworn for example.

[0052] Referring again to particular aspects of the invention, controlcircuit 140 in the example of FIG. 1a executes a partial frame capturemode in order to clock out and capture pixel data illustrated by validzone 12-1. Reading the pixel values of valid zone 12-1 is effective todecode 1D symbol 16-1 in the reader's full field of view. Given thatclocking out and capturing image data of valid zone 12-1 consumes lesstime than clocking out and capturing a full frame of image data, it isseen that execution of a partial frame capture mode decreases the decodetime of the reader. In prior art 2D optical readers, electrical signalscorresponding to full frame 10 are clocked out in order to decode asingle 1D symbol 16-1. The pixels of valid zone 12-1 may comprise asingle row of pixels (a scan line) or a plurality of rows.

[0053] In the example of FIG. 1b, control circuit 140 executes a partialframe capture mode in order to capture data defining valid zones 12-2,12-3 and 12-4 of a full frame of image data corresponding to a fullfield of view of a 2D image sensor. Valid zones 12-2, 12-3 and 12-4 areline patterns of image data at various angular orientations. Reading ofpixels of linear valid zones arranged at various angular orientations iseffective to decode a 1D symbol which may be located at an oblique anglein a field of view. It is seen that reading of pixels of linear validzone 12-3 will result in the successful decoding of 1 D bar code symbol16-2. Zones 12-2, 12-3 and 12-4 may be one or more pixels wide.

[0054] In the example of FIG. 1c, control circuit 140 executes a partialframe capture mode in order to clock out and capture image data definingvalid zones 12-5 through 12-9. Valid zones 12-5 to 12-9 form a pluralityof horizontal parallel lines. The pattern of valid zones shown in FIG.1c clocked out and captured in a partial frame capture mode is effectivefor decoding substantially horizontally oriented 1D symbols which are atan unknown height in a full field of view. It is seen that the readingof image data of valid zone 12-8 will not result in the decoding ofsymbol 16-3 because symbol 16-3 is not a 1D symbol. Nevertheless,because valid zone 12-8 intersects symbol bullseye 16 b, reading of aimage data of valid zone 12-8 may be effective to determine that a 2Dsymbol is likely present in the full field of view of image sensor 132.In one aspect of the invention, reader 110 may be configured to switchout of a partial frame capture mode and into a full frame capture modewhen reading of image data captured in the partial frame capture modereveals that a 2D symbol is likely to be represented in the image datacorresponding to the image sensor's full field of view.

[0055] The states of operation of reader 110 operating in accordancewith the invention are normally selected by actuating appropriatebuttons of keyboard 178, or control of a GUI, or by the reading ofmenuing symbols, as are explained in commonly assigned U.S. Pat. No.5,929,418 incorporated herein by reference. In alternative embodiments,software can be used to control which states of operation will be activeat different times. For example, it is possible to program a computer tobegin operation of the reader device in a default state, such as apartial frame capture mode of the 2D image sensor. It is possible towrite computer code that will switch the operation to a second partialframe imaging mode if a sensor module senses the presence of one or morefinder patterns. It is possible to write computer code that will switchthe operation to a full frame imaging mode if an analysis module revealsthe presence of a 2D encoded indicium.

[0056] It should be apparent that several operating states of theinvention are possible. In a first operating state, reader 110 is madeto operate only in a partial frame capture mode until the time the firstoperating state is deactivated.

[0057] In a second operating state, as is alluded to in the example ofFIG. 1c, the reader operates in a partial frame capture mode until thetime that reading of image data captured in the partial frame capturemode reveals that a 2D symbol is likely to be included in the full framefield of view of image sensor 132. The revelation that a 2D symbol islikely to be included in the full frame field of view of image sensor132 is accomplished using an analysis module that analyses the featuresof the partial frame of image data. When reading of the partial frame ofimage data reveals that a 2D symbol is likely to be included in a fullframe field of view, control circuit 140 captures at least one fullframe of image data from sensor 132 and attempts to decode for the 2Dsymbol determined likely to be represented in the full frame of imagedata. A reader operating in the second operating state may also be madeto switch to a full frame operating mode on the condition that a symbolis not successfully decoding during operation of the reader in thepartial frame operating mode.

[0058] A third operating state of a reader operating in accordance withthe invention is described with reference to FIGS. 1d and 1 e. Operatingin accordance with a third operating state, a reader operates in apartial frame capture mode to clock out and capture image data of validzone 12-10 which corresponds to a predetermined pattern and position infield of view 10. It is seen that reading of image data of zone 12-10will not be effective to decode symbol 16-4 because symbol 16-4 is of atype of 2D symbol known as a stacked linear bar code. Control circuit140 may nevertheless detect that symbol is a 2D symbol given that validzone 12-10 intersects a finder pattern 16 f of symbol 16-4. Sensing witha sensing module that a 2D symbol is likely present in the field of viewwhen reading the partial frame image data corresponding to valid zone12-10, the reader operating in the third operating state then continuesto operate in a partial frame mode to clock out and capture image datathat defines a second valid zone 12-11 of pixel positions as seen inFIG. 1e. The second valid zone 12-11 is not of a predetermined size andposition, but rather is of an adaptive position whose position, andpossibly size, orientation and shape depends on the result of thereading of the image data corresponding to the first valid zone 12-10.Specifically, the second valid zone 12-11 is normally at least of a sizeand position that is likely to encompass the symbol 16-4 detected to bepresent when reading of the image data of first valid zone 12-10. It isseen that the third operating state is likely to be operative to furtherreduce the clocking out and capture of irrelevant image data, andtherefore is likely to further increase decoding speed. In the thirdoperating state, additional adaptive position valid zones may be clockedout and captured if the reading of image data of first adaptive validzone 12-11 does not result in a symbol being decoded.

[0059] In the example of FIGS. 1f and 1 g valid zones 12-12 and 12-13correspond to nonlinear groupings of pixels. Capturing of the valid zonepatterns 12-12 and 12-13 of FIGS. 1f and 1 g is particularly useful fordecoding symbol image data in the case that a symbol is likely to be ata certain position in relation to an image sensor's full frame field ofview such as in the center of an image sensor's field of view as shownin FIG. 1f.

[0060] In the example of FIG. 1f control circuit 140 can successfullydecode symbol 16-6 because symbol 16-6 is located entirely within validzone 12-12.

[0061] In the example of FIG. 1g, control circuit 140 cannot decodesymbol 16-7 if operating in the first operating state since symbol 16-7is a 2D symbol and is not entirely located within valid zone 12-13. Ifoperating in the second operating state, then a reader capturing imagedata within valid zone 12-13 may successfully decode symbol 16-7 byreading the image data of zone 12-13 to determine that a 2D symbol ispresent, switching operation to a full frame capture mode to capture afull frame 10 of image data, and processing the full frame of image datato decode symbol 16-7. A reader operating in the third operating statedescribed hereinabove may decode symbol 16-7, in the example of FIG. 1g,by reading image data within valid zone 12-13, capturing image datawithin an adaptively defined valid zone (not shown) of sufficient sizeand position to encompass symbol 16-7, and then processing the imagedata within the adaptively defined valid zone to decode symbol 16-7.

[0062]FIG. 3 is a flow diagram 300 showing an illustrative process inwhich a partial frame of an image of an encoded indicium is processed toextract encoded information. The process begins as indicated in the oval310 labeled “START.” The reader images an encoded indicium using the 2Dimage sensor operating in a partial frame mode, as indicated at box 320.The control module causes a partial frame of the image to be captured orclocked out, as indicated at box 330. The processing module processesthe partial frame of image data to extract information encoded in theencoded indicium, as indicated at box 340. The result of the processingby the processing module is examined to determine whether informationhas indeed been extracted, and a test is performed as indicated bydiamond 350. If the result of the test is positive, as indicated by thearrow labeled “YES,” the information is provided, as indicated by box360. The process is then completed, as indicated by oval 370, labeled“END.” However, if the result of the test performed at step 350 isnegative, as indicated by the arrow labeled “NO,” the control moduleswitches to a full frame mode of operation, as indicated at box 355. Theresult of processing a full frame of the image is then provided at box360, and the process ends at oval 370. The process 300 can be repeatedas many times as required to extract information from a plurality ofencoded indicia.

[0063]FIG. 4 is another flow diagram 400 showing an illustrative processin which a partial frame of an image of an encoded indicium is processedto extract encoded information. The process begins as indicated in theoval 410 labeled “START.” The reader images an encoded indicium usingthe 2D image sensor operating in a first partial frame mode, asindicated at box 420. The control module causes a first partial frame ofthe image to be captured or clocked out, as indicated at box 430. Theprocessing module processes the first partial frame of image data toextract information encoded in the encoded indicium, as indicated at box440. The result of the processing by the processing module is examinedto determine whether information has indeed been extracted, and a testis performed as indicated by diamond 450. If the result of the test ispositive, as indicated by the arrow labeled “YES,” the information isprovided, as indicated by box 460. The process is then completed, asindicated by oval 470, labeled “END.” However, if the result of the testperformed at step 450 is negative, as indicated by the arrow labeled“NO,” the control module switches to a second partial frame mode ofoperation, as indicated at box 455. The second partial frame is notnecessarily of a predetermined size and position, but rather is of anadaptive position whose position, and possibly size, orientation andshape depends on the result of the reading of the image datacorresponding to the first partial frame. For example, the secondpartial frame may be determined by the sensor module, using suchinformation as one or more finder patterns, or one or morecharacteristics of known symbologies that suggest or define a size, anorientation, and/or a shape of a likely region to use as the secondpartial frame. The result of processing the second partial frame of theimage is then provided at box 460, and the process ends at oval 470. Theprocess 400 can be repeated as many times as required to extractinformation from a plurality of encoded indicia.

[0064] Yet another mode of operation is possible, in which the regionthat is examined is incrementally increased. In brief, in this operatingmode, a first partial frame of image data is clocked out and analyzed.If the data provides information, the result is presented. However, ifthe first partial frame does not provide decoded information, theoperation of the system can be switched to a second partial frame mode,and if that mode of operation also fails to provide information, theoperation can be switched to a third mode, such a full frame operatingmode. As many incrementally larger partial frames as appear useful canbe successively clocked out and analyzed in an effort to search fordecodable information. However, one must also consider as a limitationthat if the total operating time to obtain and examine a succession ofincrementally larger partial frames equals or exceeds the time requiredto clock out and analyze a full frame of data, there is no improvementin processing time to be gained. Accordingly, depending on partial frameclock out time, and depending on the processing speed of the analysismodule, one or more sequences of incrementally increasing partial frameregions can be defined beyond which it is more efficient to simplyexamine the full frame of image data. An illustrative example is givenin the flow chart depicted in FIG. 5, in which a second partial framemode is used before the full frame mode is activated.

[0065]FIG. 5 is another flow diagram 500 showing an illustrative processin which a partial frame of an image of an encoded indicium is processedto extract encoded information. The process begins as indicated in theoval 510 labeled “START.” The reader images an encoded indicium usingthe 2D image sensor operating in a first partial frame mode, asindicated at box 520. The control module causes a first partial frame ofthe image to be captured or clocked out, as indicated at box 530. Theprocessing module processes the first partial frame of image data toextract information encoded in the encoded indicium, as indicated at box540. The result of the processing by the processing module is examinedto determine whether information has indeed been extracted, and a testis performed as indicated by diamond 550. If the result of the test ispositive, as indicated by the arrow labeled “YES,” the information isprovided, as indicated by the path of arrows labeled “YES” from diamond555 through diamond 560 to box 570, labeled “PROVIDE INFORMATION.” Theprocess is then completed, as indicated by oval 580, labeled “END.”However, if the result of the test performed at step 550 is negative, asindicated by the arrow labeled “NO,” the control module switches to asecond partial frame mode of operation, as indicated at box 555. Thesecond partial frame is not necessarily of a predetermined size andposition, but rather is of an adaptive position whose position, andpossibly size, orientation and shape depends on the result of thereading of the image data corresponding to the first partial frame. Forexample, the second partial frame may be determined by the sensormodule, using such information as one or more finder patterns, or one ormore characteristics of known symbologies that suggest or define a size,an orientation, and/or a shape of a likely region to use as the secondpartial frame. In the second partial frame mode, additional informationcorresponding to the additional pixels that are to be interrogated isclocked out and the resulting partial frame of image data is analyzed. Atest of the result of processing the second partial frame of the imageis performed at diamond 560, labeled “INFORMATION EXTRACTED?” If theresult of the test is positive, as indicated by the arrow labeled “YES,”the information is provided, as indicated by box 570. The process isthen completed, as indicated by oval 580, labeled “END.” However, if theresult of the test performed at step 560 is negative, as indicated bythe arrow labeled “NO,” the control module switches to a full frame modeof operation, as indicated at box 565. The result of processing a fullframe of the image is then provided at box 570, and the process ends atoval 580. The process 500 can be repeated as many times as required toextract information from a plurality of encoded indicia.

[0066] Those of ordinary skill will recognize that many functions ofelectrical and electronic apparatus can be implemented in hardware (forexample, hard-wired logic), in software (for example, logic encoded in aprogram operating on a general purpose processor), and in firmware (forexample, logic encoded in a non-volatile memory that is invoked foroperation on a processor as required). The present inventioncontemplates the substitution of one implementation of hardware,firmware and software for another implementation of the equivalentfunctionality using a different one of hardware, firmware and software.To the extent that an implementation can be represented mathematicallyby a transfer function, that is, a specified response is generated at anoutput terminal for a specific excitation applied to an input terminalof a “black box” exhibiting the transfer function, any implementation ofthe transfer function, including any combination of hardware, firmwareand software implementations of portions or segments of the transferfunction, is contemplated herein.

[0067] While the present invention has been explained with reference tothe structure disclosed herein, it is not confined to the details setforth and this invention is intended to cover any modifications andchanges as may come within the spirit and scope of the following claims.

We claim:
 1. A method of conducting a business transaction involvinginformation recorded in an encoded indicium, the method comprising thesteps of: operating an optical reader having a 2D image sensor;capturing with the 2D image sensor a partial frame of image data from anencoded indicium; and processing image data of said partial frame ofimage data to extract information encoded by the encoded indiciumwhereby the purposes of the business transaction are advanced.
 2. Themethod of claim 1, wherein said capturing step includes the step ofcapturing image data corresponding to a linear pattern of pixels.
 3. Themethod of claim 1, wherein said capturing step includes the step ofcapturing image data corresponding to a plurality of angularly offsetlinear patterns of pixels.
 4. The method of claim 1, wherein saidcapturing step includes the step of capturing image data correspondingto a plurality of vertically spaced apart horizontally oriented linearpatterns of pixels.
 5. The method of claim 1, wherein said capturingstep includes the step of capturing image data corresponding to agrouping of pixels about a center of said image sensor.
 6. The method ofclaim 1, wherein said processing step includes the step of reading saidimage data out of a memory device.
 7. The method the claim 1, whereinsaid processing step includes the steps of reading said image data outof a memory device and attempting to decode for a decodable symbol whichmay be represented in said image data.
 8. The method of claim 1, whereinsaid method further includes the step of capturing a full frame of imagedata if said processing step reveals that a 2D symbol is likelypartially represented in said partial frame of image data.
 9. The methodof claim 1, wherein said method further includes the step of capturingan adaptively positioned partial frame of image data if said processingstep reveals that a 2D symbol is likely partially represented in saidpartial frame of image data.
 10. The method of claim 1, wherein saidprocessing step includes the step of attempting to decode for adecodable symbol represented in said image data, said method furtherincluding the step of capturing a full frame of image data if saidprocessing step reveals that a 2D symbol is likely partially representedin said partial frame of image data.
 11. A method of conducting abusiness transaction involving information recorded in an encodedindicium, said method comprising the steps of: (a) operating an opticalreader having a 2D image sensor; (b) in a partial frame operating mode,capturing a partial frame of image data, the partial from of image dataincluding at least a portion of the encoded indicium; (c) attempting toextract information encoded by the encoded indicium from the capturedpartial frame of image data; and (d) if in step (c) the reader fails toextract information encoded by the encoded indicium, switching operationof the reader to a full frame capture mode.
 12. The method of claim 11,wherein said capturing step includes the step of capturing image datacorresponding to a linear pattern of pixels.
 13. The method of claim 11,wherein said capturing step includes the step of capturing image datacorresponding to a plurality of angularly offset linear patterns ofpixels.
 14. The method of claim 11, wherein said capturing step includesthe step of capturing image data corresponding to a plurality ofvertically spaced apart horizontally oriented linear patterns of pixels.15. The method of claim 11, wherein said capturing step includes thestep of capturing image data corresponding to a grouping of pixels abouta center of said image sensor.
 16. A method of conducting a businesstransaction involving information recorded in an encoded indicium, saidmethod comprising the steps of: (a) operating an optical reader having a2D image sensor; (b) in a partial frame operating mode, capturing apartial frame of image data, the partial from of image data including atleast a portion of the encoded indicium; (c) attempting to extractinformation encoded by the encoded indicium from the captured partialframe of image data; and (d) if in step (c) the reader fails to extractinformation encoded by the encoded indicium, switching operation of thereader to a second partial frame capture mode.
 17. The method of claim16, wherein said capturing step includes the step of capturing imagedata corresponding to a linear pattern of pixels.
 18. The method ofclaim 16, wherein said capturing step includes the step of capturingimage data corresponding to a plurality of angularly offset linearpatterns of pixels.
 19. The method of claim 16, wherein said capturingstep includes the step of capturing image data corresponding to aplurality of vertically spaced apart horizontally oriented linearpatterns of pixels.
 20. The method of claim 16, wherein said capturingstep includes the step of capturing image data corresponding to agrouping of pixels about a center of said image sensor.
 21. The methodof claim 16, further comprising the step of switching operation of thereader to a full frame operating mode if the reader fails to extractinformation encoded by the encoded indicium from data captured using thesecond partial frame capture mode.
 22. An apparatus for conducting abusiness transaction involving information recorded in an encodedindicium, the apparatus comprising: an optical reader having a 2D imagesensor configured to image an encoded indicium; a control moduleconfigured to operate the 2D image sensor to capture a partial frame ofimage data from the encoded indicium; and a processing module configuredto process the partial frame of image data to extract therefrominformation encoded by the encoded indicium, whereby the purposes of thebusiness transaction are advanced.
 23. The apparatus according to claim22, further comprising: an analysis module configured to deduce that a2D encoded indicium is present in the partial frame of image data. 24.The apparatus according to claim 23, further comprising: a controlmodule that configures the 2D sensor to operate in a full frameoperating mode.
 25. The apparatus according to claim 22, furthercomprising: a sensor module configured to sense that a 2D encodedindicium is present in the partial frame of image data.
 26. Theapparatus according to claim 25, further comprising: a control modulethat configures the 2D sensor to operate in a second partial frameoperating mode.